Abstract Detail

Endemic plants make up ~ 90% of the native vascular plant flora of the Hawaiian Islands. These 1000+ species arose from an est. 263-270 initial colonists that arrived by long-distance dispersal. Most of these were thought to be relatively young, arriving within the past 5.1-0.5 MY and be from source areas in the tropical Pacific. The lineages with multiple species, such as silverswords, were also thought to be the product of multiple colonization events. Molecular phylogenetic studies have shown, however, that these ideas are now largely outdated. Among the oldest are Hillebrandia (51-65 MYA) from Malesia, and most geographically unexpected, Hesperomannia, derived from an African/Madagascan colonist estimated to have diverged from its ancestor 17-26 + 1-3.43 MYA. There are also lineages derived from arctic-boreal ancestors (Viola, Vaccinium, Schiedea) and western North America (the well known silversword alliance, Chamaescyce, Bidens, Plantago, Geranium, and the mints (Phyllostegia, Stenogyne,Haplostachys)), along with others. Additionally, a number of Asian/Australasian/ Pacific lineages occur in the islands varying in age from 1< to > 12 MYA (e.g., Santalum 0.4-0.6MYA, Metrosideros 1.4-6.3 MYA, lobelioids 13 MYA). Most taxa were found to be the result of a single colonization, regardless of species numbers and habitat types; the only exceptions to the one ancestor rule being Scaevola with three, the dryopteroids with three to five, and Santalum with two separate colonization events, respectively. Additionally, it was discovered that Hawaii is the source o fcolonists for other islands, not just the endpoint of Pacific floral migrations.